Looks like vegetarians and vegans may be onto something.

A new study, published in the journal Cell Metabolism, showed people who ate a diet high in animal proteins from milk, meat, and cheese were 74 percent more likely to die earlier and more likely to be diagnosed with diabetes or develop cancer than those who follow a diet low in protein.

The study looked at the hormone IGF-I, which is controlled by protein and helps your body grow. It is also linked to cancer susceptibility.

"The research shows that a low-protein diet in middle age is useful for preventing cancer and overall mortality, through a process that involves regulating IGF-I and possibly insulin levels," Eileen Crimmins, a co-author on the study, said in a news release.

Researchers followed more than 6,000 adults over the age of 50 for 20 years and found that the hormone is less prevalent in people over the age of 65. Researchers noted, however, that a low-protein diet may not be ideal for elderly people as it can lead to unhealthy weight management and frailty.

A high-protein diet was defined by the researches as 20 percent of calories coming from both animal and plant-based sources of protein. Moderate ranged from 10 to 19 percent and low-protein was defined as less than 10 percent. People who ate a diet with moderate protein were still three times more likely to die of cancer than those with a low-protein intake.

The study also found that eating plant-based proteins was healthier than eating animal-based protein.

“The majority of Americans are eating about twice as much proteins as they should, and it seems that the best change would be to lower the daily intake of all proteins, but especially animal-derived proteins," said Valter Longo, a co-author in the study and professor of Biogerontology at the USC Davis School of Gerontology and director of the USC Longevity Institute.